The present invention relates to an air compressor with a catalyst disposed in a reception block.
Air compressors generate compressed air by drawing and compressing ambient air. They are utilized in the industry and often also on trucks in order to provide compressed air for the brake system or for the vehicle spring or damper system. The compressed gas is thereby almost inevitably contaminated with oil aerosols and oil vapor, all the more so if the air compressors are operated with oil lubrication. Due to the small amount of leakage between pistons and cylinders, the oil aerosols and the oil vapor are transported with the supplied compressed air into the compressed air system. The amount of contamination thereby depends on the operating conditions such as temperature, compressed air volume flow or component tolerances.
For a plurality of applications, such type contamination is undesirable or even unacceptable. Presently, no compressors are known which are capable of generating oil-free compressed gases without having to additionally process them. Although compressors for oil-free compression of gas or compressed air are available, the compressed air they generate still comprises at least small amounts of, for example, organic impurities. This results, inter alia, from the fact that the compressions absorb impurities from ambient air. The oil contaminates and, as a result thereof, affects the function of the components mounted downstream thereof. When the compressed air, which has been used, is vented to the atmosphere, this also has an impact on the environment.
For this reason, one usually utilizes filter systems mounted downstream thereof which are to ensure appropriate quality of the compressed air. Substantially, absorption filters made from activated carbon are known, but they have a short life. One also utilizes the catalytic combustion of the oil contained in the compressed air, using what are referred to as oxidation catalysts. Put simply, the oil, which is contained in the compressed air in the form of hydrocarbon compounds (CH groups), is chemically broken down to carbon dioxide (CO2) and water (H2O) in an exothermic reaction. This method is in particular known from the automotive field and is utilized for both gas and diesel engines. In process engineering, oxidation catalysts are also utilized for cleaning contaminated exhausts.
U.S. Pat. No. 5,284,629 A describes a method of removing compressor oil from compressed air wherein the compressed air is led through a tank in which there is located a layer of an oxidation catalyst. Metallic components selected from the group consisting of platinum, palladium, nickel, cobalt, iron, rhodium, manganese and copper are indicated as the materials used for oxidation catalysts.
The document DE 100 08 609 C1 further describes a similar method wherein a hopcalite material is utilized as the oxidation catalyst. Hopcalite is the name for mixed oxidation catalysts mainly consisting of manganese dioxide and copper(II) oxide. They may also contain additional metal oxides such as cobalt oxide and silver (I) oxide.
The document WO 00/66251 also describes an apparatus for cleaning compressed air with the help of an oxidation catalyst mounted downstream of an air compressor.
These systems are supplied with electrical energy in order to achieve the required reaction temperature of the oxidation catalyst. Moreover, they must be disposed as additional components in the region of the air compressors, which means that they need space and mounting expense in accordance therewith. Heat exchangers are also needed as well as appropriate equipment for controlling the electronics. In particular in case of smaller amounts of compressed air, such type oxidation catalysts are disproportionally expensive.
The document EP 136 37 21, as well as the document DE 199 02 052 C2, describe the integration of oxidation catalysts in the air compressor itself. According to DE 199 02 052 C2, the oxidation catalyst is embedded in a horizontal portion of a throttle output and extends as far as the outer wall side of the cylinder head. The apparatus according to EP 136 37 21 is similar, with the oxidation catalyst being also disposed in the outlet of a cylinder. The apparatus described in these printed documents require that the oxidation catalyst material be mounted in the outlet channel. For this purpose, it is necessary to change the construction of the cylinder head or of the outlet channel since otherwise the quantity of oxidation catalyst material will not suffice. Moreover, the oxidation catalyst is difficult to maintain or replace. Finally, it seems unavoidable to rebuild the cylinder.